1. Field of the Invention
This invention relates generally to bipolar memory cells and, more particularly, to bipolar memory cells having an AC transient driver for improving the downward transition of the row select line without substantially increasing power requirements.
2. Background Art
Memory cells are circuits wherein information may be stored in a low current stand-by mode and may be written or read in a higher current mode. A typical bipolar memory cell is illustrated in FIG. 1 and is also described in detail in the Detailed Description of the Preferred Embodiment. This previously known circuit comprises a plurality of memory cells wherein each typically includes a pair of multi-emitter transistors coupled between a row select line and a current drain line to function as a latch in a manner well known to those skilled in the art. Resistive loads are coupled between each transistor and the row select line. A row driver transistor is coupled between a first supply voltage terminal and the row select line and is responsive to a select signal. A current source transistor is coupled between the current drain line and a second supply voltage terminal.
A first and second discharge transistor are coupled between the row select line and the current drain line, respectively, and the second supply voltage terminal. A first diode is coupled between the row select line and the first discharge transistor and a second diode is coupled between the current drain line and the second discharge transistor.
Another previously known method similar to the above method includes logic circuitry for determining when the downward transition occurs, and which sends additional current to the NPN current source transistor 22 for a speedier discharge of the inherent capacitance. However, this method requires additional current and sophisticated timing which are extremely detrimental in memory cells, especially as the size of memory increases.
Thus, what is needed is an improved AC transient driven circuit for memory cells that provides an improved downward transition without a requirement for additional power.